Devices and methods of this kind are used in electrical connection technology, for example, to make a connection which is no longer releasable between a cable and a connecting element. The cable and the connecting element are in this case connected to each other by plastic deformation, which is brought about by a pressing force. By a connection of this kind, the cable and the connecting element can further be contacted electrically, wherein the connecting element can be designed as any contact element, e.g. as a plug.
The connection between the cable and the connecting element can be made by crimping or splicing, for example. In the case of crimping, usually preformed connecting elements are used, of which the dimensions, particularly their length, are coordinated with the cross-section of the cable. Further, crimping tools have predetermined profiles for bringing about a presettable deformation of the cable and of the connecting element and so forming the crimped connection in a desired shape. In the case of splicing, an endless tape is used instead of a preformed connecting element.
At its simplest, a crimped connection can be produced by means of crimping pliers. If, however, a large number of crimped connections are to be produced within a short time, for example in the manufacture of special cables with special contact elements, automated devices are used. A device of this kind is shown schematically in FIG. 1 and comprises an upper die in which a punch-like lower die engages. The cable and the connecting element pass between pressing surfaces of the upper and lower dies and are pressed together by means of a pressing force which is exerted on the upper or lower die.
As the outer shape of the crimped connection is to be defined by the shape of the pressing surfaces of the upper and lower dies, an extremely small gap between the flanks or side surfaces of the upper and lower dies is necessary. In practice, when making the crimped connection various kinds of errors can nevertheless arise. For instance, the connecting element can already be deformed before it reaches the device. The cable and the connecting element can be displaced or rotated relative to a centre axis of the upper and lower dies. Further, the upper and lower dies can be displaced relative to each other.
As a result, so-called miscrimping can occur, in which material of the cable and/or of the connecting element escapes from the predetermined region between the pressing surfaces and passes between the flanks or side surfaces of the upper and lower dies. Since material of the cable and/or connecting element which is misguided in this way is usually distributed asymmetrically in relation to the centre axis of the upper and lower dies, high torques act on the side surfaces of the upper and lower dies in case of miscrimping, due to the high pressing force. As a result, the upper and lower dies can be displaced relative to each other, and high mechanical stresses occur. Due to the stresses, the upper and lower dies can be deformed or even destroyed. The two side surfaces of the upper die can for example be bent apart by the stresses until a section of the upper die breaks off. Further, the side surfaces and pressing surfaces of the upper and lower dies are greatly stressed by the mechanical stresses, so that grooves can form in the pressing surfaces. Thus miscrimping reduces the life of the upper and lower dies.
It is therefore the object of the invention to provide a device and a method of the kind described above for attaching a cable to a connecting element, by which the probability of damage to an upper and a lower die is reduced if erroneous attachment occurs.